When the Labor Department puts out the January employment figures on Feb. 4, they will include an assumption that a lot of companies went out of business.

This is something called the birth/death model that is used by the department. Last year it caused 356,000 jobs to be subtracted from the January job count.

So, the next employment figure should be shockingly bad.

Fact 2: The birth/death model will then turn optimistic in the spring, causing jobs that really don't exist to be added to the Labor Department's count.

It won't make the people who are unemployed feel any better. But it could give Wall Street another excuse to rally and, really, isn't that what it is all about?

Fact 3: Nobody in the media will pick up on this, but the Labor De partment will also do something called a benchmark revision on Feb. 4 that will subtract around 840,000 jobs that the government thought existed, but really don't.

This will mostly make up for the mistakes created by the birth/death model.

Fact 4: That 840,000 job adjustment will only correct errors up to March 2009. Mistakes for the April 2009 to March 2110 period will be corrected next year.

Fact 5: You keep reading that the unemployment rate stayed at 10 percent. But the press has been playing up the 17.3 percent rate that includes those "underemployed," meaning they can't find a full-time job but want one.

I've been mentioning that under-employed figure -- called U-6 by the Labor Department -- for years and I'm glad everyone else has finally caught up.

But that larger figure doesn't include a huge number of unemployed folks who have given up looking for work because they feel the search is hopeless. Last Friday's report said 661,000 such people left the labor force in December.

If you count these hopelessly unemployed, the real jobless rate is probably close to 22 percent. If these all weren't such important issues, this would all be a big joke. john.crudele@nypost.com